A method for automatic estimation of the location of the pith, i.e., the centre of the annual rings, in wood log end images is presented. The images used are images of untreated log ends in saw mill environments taken with a standard digital camera. The method consists of three major steps: calculating local orientation in each pixel to compute the normal directions of the annual rings, determining where in the image these normal directions intersect, and refining the result by scalar multiplication with a filter with the properties of a circular pattern.